// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";

package google.cloud.texttospeech.v1;

import "google/api/annotations.proto";

option cc_enable_arenas = true;
option csharp_namespace = "Google.Cloud.TextToSpeech.V1";
option go_package = "google.golang.org/genproto/googleapis/cloud/texttospeech/v1;texttospeech";
option java_multiple_files = true;
option java_outer_classname = "TextToSpeechProto";
option java_package = "com.google.cloud.texttospeech.v1";
option php_namespace = "Google\\Cloud\\TextToSpeech\\V1";


// Service that implements Google Cloud Text-to-Speech API.
service TextToSpeech {
  // Returns a list of [Voice][google.cloud.texttospeech.v1.Voice]
  // supported for synthesis.
  rpc ListVoices(ListVoicesRequest) returns (ListVoicesResponse) {
    option (google.api.http) = {
      get: "/v1/voices"
    };
  }

  // Synthesizes speech synchronously: receive results after all text input
  // has been processed.
  rpc SynthesizeSpeech(SynthesizeSpeechRequest) returns (SynthesizeSpeechResponse) {
    option (google.api.http) = {
      post: "/v1/text:synthesize"
      body: "*"
    };
  }
}

// The top-level message sent by the client for the `ListVoices` method.
message ListVoicesRequest {
  // Optional (but recommended)
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tag. If
  // specified, the ListVoices call will only return voices that can be used to
  // synthesize this language_code. E.g. when specifying "en-NZ", you will get
  // supported "en-*" voices; when specifying "no", you will get supported
  // "no-*" (Norwegian) and "nb-*" (Norwegian Bokmal) voices; specifying "zh"
  // will also get supported "cmn-*" voices; specifying "zh-hk" will also get
  // supported "yue-*" voices.
  string language_code = 1;
}

// The message returned to the client by the `ListVoices` method.
message ListVoicesResponse {
  // The list of voices.
  repeated Voice voices = 1;
}

// Description of a voice supported by the TTS service.
message Voice {
  // The languages that this voice supports, expressed as
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tags (e.g.
  // "en-US", "es-419", "cmn-tw").
  repeated string language_codes = 1;

  // The name of this voice.  Each distinct voice has a unique name.
  string name = 2;

  // The gender of this voice.
  SsmlVoiceGender ssml_gender = 3;

  // The natural sample rate (in hertz) for this voice.
  int32 natural_sample_rate_hertz = 4;
}

// The top-level message sent by the client for the `SynthesizeSpeech` method.
message SynthesizeSpeechRequest {
  // Required. The Synthesizer requires either plain text or SSML as input.
  SynthesisInput input = 1;

  // Required. The desired voice of the synthesized audio.
  VoiceSelectionParams voice = 2;

  // Required. The configuration of the synthesized audio.
  AudioConfig audio_config = 3;
}

// Contains text input to be synthesized. Either `text` or `ssml` must be
// supplied. Supplying both or neither returns
// [google.rpc.Code.INVALID_ARGUMENT][]. The input size is limited to 5000
// characters.
message SynthesisInput {
  // The input source, which is either plain text or SSML.
  oneof input_source {
    // The raw text to be synthesized.
    string text = 1;

    // The SSML document to be synthesized. The SSML document must be valid
    // and well-formed. Otherwise the RPC will fail and return
    // [google.rpc.Code.INVALID_ARGUMENT][]. For more information, see
    // [SSML](/speech/text-to-speech/docs/ssml).
    string ssml = 2;
  }
}

// Description of which voice to use for a synthesis request.
message VoiceSelectionParams {
  // The language (and optionally also the region) of the voice expressed as a
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tag, e.g.
  // "en-US". Required. This should not include a script tag (e.g. use
  // "cmn-cn" rather than "cmn-Hant-cn"), because the script will be inferred
  // from the input provided in the SynthesisInput.  The TTS service
  // will use this parameter to help choose an appropriate voice.  Note that
  // the TTS service may choose a voice with a slightly different language code
  // than the one selected; it may substitute a different region
  // (e.g. using en-US rather than en-CA if there isn't a Canadian voice
  // available), or even a different language, e.g. using "nb" (Norwegian
  // Bokmal) instead of "no" (Norwegian)".
  string language_code = 1;

  // The name of the voice. Optional; if not set, the service will choose a
  // voice based on the other parameters such as language_code and gender.
  string name = 2;

  // The preferred gender of the voice. Optional; if not set, the service will
  // choose a voice based on the other parameters such as language_code and
  // name. Note that this is only a preference, not requirement; if a
  // voice of the appropriate gender is not available, the synthesizer should
  // substitute a voice with a different gender rather than failing the request.
  SsmlVoiceGender ssml_gender = 3;
}

// Description of audio data to be synthesized.
message AudioConfig {
  // Required. The format of the requested audio byte stream.
  AudioEncoding audio_encoding = 1;

  // Optional speaking rate/speed, in the range [0.25, 4.0]. 1.0 is the normal
  // native speed supported by the specific voice. 2.0 is twice as fast, and
  // 0.5 is half as fast. If unset(0.0), defaults to the native 1.0 speed. Any
  // other values < 0.25 or > 4.0 will return an error.
  double speaking_rate = 2;

  // Optional speaking pitch, in the range [-20.0, 20.0]. 20 means increase 20
  // semitones from the original pitch. -20 means decrease 20 semitones from the
  // original pitch.
  double pitch = 3;

  // Optional volume gain (in dB) of the normal native volume supported by the
  // specific voice, in the range [-96.0, 16.0]. If unset, or set to a value of
  // 0.0 (dB), will play at normal native signal amplitude. A value of -6.0 (dB)
  // will play at approximately half the amplitude of the normal native signal
  // amplitude. A value of +6.0 (dB) will play at approximately twice the
  // amplitude of the normal native signal amplitude. Strongly recommend not to
  // exceed +10 (dB) as there's usually no effective increase in loudness for
  // any value greater than that.
  double volume_gain_db = 4;

  // The synthesis sample rate (in hertz) for this audio. Optional.  If this is
  // different from the voice's natural sample rate, then the synthesizer will
  // honor this request by converting to the desired sample rate (which might
  // result in worse audio quality), unless the specified sample rate is not
  // supported for the encoding chosen, in which case it will fail the request
  // and return [google.rpc.Code.INVALID_ARGUMENT][].
  int32 sample_rate_hertz = 5;
}

// The message returned to the client by the `SynthesizeSpeech` method.
message SynthesizeSpeechResponse {
  // The audio data bytes encoded as specified in the request, including the
  // header (For LINEAR16 audio, we include the WAV header). Note: as
  // with all bytes fields, protobuffers use a pure binary representation,
  // whereas JSON representations use base64.
  bytes audio_content = 1;
}

// Gender of the voice as described in
// [SSML voice element](https://www.w3.org/TR/speech-synthesis11/#edef_voice).
enum SsmlVoiceGender {
  // An unspecified gender.
  // In VoiceSelectionParams, this means that the client doesn't care which
  // gender the selected voice will have. In the Voice field of
  // ListVoicesResponse, this may mean that the voice doesn't fit any of the
  // other categories in this enum, or that the gender of the voice isn't known.
  SSML_VOICE_GENDER_UNSPECIFIED = 0;

  // A male voice.
  MALE = 1;

  // A female voice.
  FEMALE = 2;

  // A gender-neutral voice.
  NEUTRAL = 3;
}

// Configuration to set up audio encoder. The encoding determines the output
// audio format that we'd like.
enum AudioEncoding {
  // Not specified. Will return result [google.rpc.Code.INVALID_ARGUMENT][].
  AUDIO_ENCODING_UNSPECIFIED = 0;

  // Uncompressed 16-bit signed little-endian samples (Linear PCM).
  // Audio content returned as LINEAR16 also contains a WAV header.
  LINEAR16 = 1;

  // MP3 audio.
  MP3 = 2;

  // Opus encoded audio wrapped in an ogg container. The result will be a
  // file which can be played natively on Android, and in browsers (at least
  // Chrome and Firefox). The quality of the encoding is considerably higher
  // than MP3 while using approximately the same bitrate.
  OGG_OPUS = 3;
}
